The present disclosure generally pertains to anchoring devices that can be used in connection with a transcatheter valve prosthesis.
Heart valve disease may either be congenital or develop over a period of time and often materializes without notice. Where possible, patients are monitored and instructed to make lifestyle changes. However, where the function of the valve becomes significantly impaired, the only option may be heart valve replacement or repair.
There are two general types of heart valve replacement procedures. The first type is surgical replacement where the patient is placed on a heart and lung machine to undergo open heart surgery. The heart is stopped so that the diseased valve may be surgically removed and replaced by a prosthetic valve that may be sutured or otherwise implanted into the same general location. This type of procedure is often the first consideration because of its long-term efficacy. However, open heart surgery is highly invasive and includes many attendant risks with the potential to be very severe or life threatening. Aside from the physical trauma of invading one of the most crucial areas of the human body, the risks are compounded by the heart and lung machine, which, among other things, can damage red blood cells leading to neurological deficiencies.
Due to these attendant risks, surgical valve replacement may not be a viable option, particularly for the elderly and frail. Additionally, individuals who receive surgical replacements earlier in life may need to have a follow-up replacement, which would likely be performed at an age where open heart surgery may be too risky. Thus, transcatheter valve implantation may be the best approach as the other type of heart valve replacement procedure. Transcatheter valve implantation is generally achieved by guiding, often percutaneously, a catheter which retains an expandable prosthetic valve, through a patient's cardiovascular system to the target, diseased valve. The prosthetic valve is deployed such that the diseased valve is pushed out of the way so that the prosthetic valve can take over. Expandable prosthetic valves are primarily comprised of porcine or bovine tissue that is sewn to a stent that includes struts forming individually expandable cells. The stent may be made from a shape memory metal, such as Nitinol, which gives it a natural bias toward an expanded state in order to hold the prosthetic valve in place.
Transcatheter valve implantation is currently indicated only for patients with severe stenosis. The primary reason for this limitation is valve migration/embolization. While the natural bias of the stent helps exert significant radial force against the surrounding soft tissue, this radial force typically is not enough to counteract the force of blood flow and gyrations from the beating heart. Thus, transcatheter valve implantation is indicated only for severe cases of stenosis so that the stent has a stable anchoring structure, such as calcium or plaque deposits, along the soft tissue of the native heart valve. Patients with congenital defects, sclerosis and/or stenosis without sufficient build-up of calcium or other deposits for anchoring the transcatheter valve may not qualify for either type of valve replacement procedure yet may suffer from valvular insufficiency.